If you unfortunately tried to upgrade to the latest and your hub seems to be broken now then please follow these steps to roll the update back:

open a SSH client like Putty to connect to your hub by SSHUsers of a Popp Hub 1 may find the ssh password in a file called password.txt stored on the boot section of the SD card. To read it out make your Popp Hub powerless, remove the SD card and put it into a card reader (maybe you need an adapter for micro SD card too) to read it out on your computer. Open the directory of the SD card and write down the password from password.txt. Eject the SD card and put it back into your Popp Hub 1 - be carefully sometimes the card can slip between the tiny slots and you need to open the case.
Enter the IP of your Hub and click on Open

These steps can restore your old installations independent on which platform and OS you are (except WD NAS and Popp Hub 2).

Note:
This won't heal a controller factory reset. Therfore a controller backup is necessary to revert it.
But luckily if the the controller isn't touched by such issue, everything will be there after downgrade.

In any other case of problems please contact the Support:
support(at)z-wave.eu (DE/EN)
razberry(at)z-wave.me (RU/EN/FR)